Construction of Cryptogein Mutants, a Proteinaceous Elicitor fromPhytophthora, with Altered Abilities To Induce a Defense Reaction in Tobacco Cells

Abstract

We prepared a series of cryptogein mutants, an elicitor from Phytophthora cryptogea, with altered abilities to bind sterols and fatty acids. The induction of the early events, i.e., synthesis of active oxygen species and pH changes, in suspension tobacco cells by these mutated proteins was proportional to their ability to bind sterols but not fatty acids. Although the cryptogein-sterol complex was suggested to be a form triggering a defense reaction in tobacco, some proteins unable to bind sterols induced the synthesis of active oxygen species and pH changes. The modeling experiments showed that conformational changes after the introduction of bulky residues into the omega loop of cryptogein resemble those induced by sterol binding. These changes may be necessary for the ability to trigger the early events by elicitins. However, the ability to stimulate necrosis in suspension tobacco cells and the expression of defense proteins in tobacco plants were linked neither to the lipid binding capacity nor to the capacity to provoke the early events. On the basis of these experiments and previous results, we propose that elicitins could stimulate two signal pathways. The first one induces necroses and the expression of pathogen-related proteins, includes tyrosine protein kinases and mitogen-activated protein kinases, and depends on the overall structure and charge distribution. The second type of interaction is mediated by phospholipase C and protein kinase C. It triggers the synthesis of active oxygen species and pH changes. This interaction depends on the ability of elicitins to bind sterols.

Transcriptional Programming and Functional Interactions within the Phytophthora sojae RXLR Effector Repertoire

“…Elicitins are small (10 kD) disulfide-bonded sterol carrier proteins produced by all Phytophthora species. The responses of tobacco (Nicotiana tabacum) tissues to the elicitins cryptogein and INF1 from Phytophthora cryptogea and P. infestans, respectively, have been characterized extensively (Boissy et al, 1996;Kamoun et al, 1998aKamoun et al, , 1998bKanzaki et al, 2003;Lherminier et al, 2003;Huitema et al, 2005;Lochman et al, 2005;Kanneganti et al, 2006;Svozilová et al, 2009). The extent to which ETI and PTI involve distinct mechanisms is still an open question (Jones and Dangl, 2006;Lee et al, 2009;Thomma et al, 2011).…”

Transgenic mimicry of pathogen attack stimulates growth and secondary metabolite accumulation

“…It elicits a defense response in tobacco through interaction with a receptor, followed by signal transduction, which leads to the expression of a transcription factor (Lecourieux et al 2002;Guo et al 2004;Kasparovsky et al 2004;Lochman et al 2005;Ren et al 2006), which in turn is thought to be responsible for a generalized stress response. Knowledge of the amino acid sequence of the Crypt protein (Ricci et al 1989) allowed the synthesis of a crypt gene, whose expression in Escherichia coli led to the production of Crypt protein that induced (in tobacco) the necrosis associated with the defense response (O'Donohue et al 1995).…”

Nicotiana tabacumTTG1 contributes to ParA1-induced signalling and cell death in leaf trichomes

“…Many of the papers touched on causal relationships between ROS and HCD or the defence response. They were concomitant, but the consequence was unclear in most reports (Bourque et al, 1998;Fleischmann et al, 2005;Kanzaki et al, 2008;Koehl et al, 2007;Lebrun-Garcia et al, 1998;Lecourieux et al, 2002;Liang et al, 2007;Lochman et al, 2005;Rusterucci et al, 1996;Yoshioka et al, 2003). Several reports argued that ROS or H 2 O 2 was elevated but was not required for the elicitation of HCD and defence response in tobacco following treatment with Phytophthora megasperma megaspermin (Dorey et al, 1999) or P. cryptogea cryptogein (Binet et al, 2001;Rustérucci et al, 1999).…”

“…During infection of plants, sterols required for pathogenic oomycetes to growth are supplied via the triple complex, which captures and carries sterols diffused from the host plants and then transports the compounds to oomycete cells (Blein et al, 2002;Mikes et al, 1998;Vauthrin et al, 1999). Second, regarding molecular recognition and subsequent response, the NtTTG1-ParA1 interaction differs from plant perception to some other elicitins, such as INF1 (Kanzaki et al, 2008) and cryptogein (Lochman et al, 2005;Pugin et al, 1997); both elicitins have been shown to induce H 2 O 2 production and HCD by activating plant signalling processes independent of sterol binding. In tobacco, for example, a lectin-like receptor-kinase protein functions to bind INF1 and the binding activity is required for INF1 to induce H 2 O 2 and HCD (Zhao et al, 2008).…”

“…In tobacco, for example, a lectin-like receptor-kinase protein functions to bind INF1 and the binding activity is required for INF1 to induce H 2 O 2 and HCD (Zhao et al, 2008). Hence, different plant proteins are required for interactions with different types of elicitins during the distinct processes, such as oomycete infection and plant response to the extrinsic application of elicitins (Blein et al, 2002;Kanzaki et al, 2008;Lochman et al, 2005). Finally, considering the diversity of plant extrinsic cues, one could believe that NtTTG1-ParA1 interaction presents an example that trichomes function like biological antennae to sense outside signals.…”